1. Field of the Invention
The present invention relates to an arrangement for sensing the position of a leader pin on a tape which is located within a cartridge shell. More particularly, the invention relates to an arrangement for sensing the position of a pin in a tape cartridge through the intermediary of either electromagnetic sensors or electrostatic detection means. Additionally, the invention is directed to the provision of a method of sensing the position of a pin on a tape inside a cartridge shell by employing either electrostatic detection means or electromagnetic sensors.
In the technology which is directed to tape loading apparatus, and especially in connection with high-speed precision machines for automatically loading predetermined amounts of magnetic tape into a media cassette, it is of extreme importance to be able to reliably effect the picking and/or or positioning or placement of a leader pin in media cartridges, for instance, such as but not limited to LTO cartridges, in order to obtain the necessary degree of tape drive reliability. In essence, this entails having precise knowledge over the location of the pin prior to attempting a pick, monitoring the position of the pin during picking or placement, and also being able to be able to ascertain that the pin has been properly placed so as to ensure the reliability of the tape loading operation.
In essence, a difficulty which is encountered in obtaining a precise sensing of the pin location within the cartridge shell, wherein the pin is attached to the tape or a tape leader portion, resides in that the location of the pin is normally considerably retracted within the confines of the cartridge, which is attendant with an extremely tight mechanical spacing therein. Consequently, it is extremely difficult to precisely be able to sense the location of the pin within the cartridge in the absence of any small, delicate or essentially complex mechanisms which are capable of reaching well into the interior of the media cartridge.
In the present state-of-the technology, the sensing or detection of the precise location of the pin on the tape within the cartridge shell is an essentially difficult and complex operation. Pursuant to the current state-of-the art, a drive for the cartridge magnetic tape may entail implements such as small levers on a picking mechanism adapted to physically move when the pin is positioned to extend into the picking mechanism. The prior art structure fails to provide any capability of being able to detect if the pin is in its proper location or orientation prior to attempting to pick the pin, and also exposes the mechanism to a potential hang-up or dislodging of the pin if out of place or dislocated within the tape cartridge. Furthermore, the design of the mechanism in the state-of-the art is also extremely small in size and, resultingly, fragile in nature due to the demands of the tight space within which it is designed to implement mechanical sensing in a tape cartridge, for instance, such as an LTO cartridge, and consequently is prone to reliability problems in the operation or functioning thereof.
2. Discussion of the Prior Art
Although various arrangements are presently known for sensing pin locations in magnetic tape or media cassettes, none of these are directed to essentially electromagnetic or electrostatic detection or sensing arrangements or methods as contemplated by the present invention.
Garcia et al. U.S. Pat. No. 5,576,905, which is commonly assigned to the present assignee, relates to a servo control for a bi-directional reel-to-reel tape drive employing fine-line tachometers with index lines. In this connection, sensing of pin locations is implemented through the intermediary of tachometers in order to enable the by-directional recording and playback of information in either tape direction. In that particular instance optical sensors are utilized in a tachometer assembly to produce index pulses on a signal line whenever a index line is at a predetermined reference position in a tachometer. This enables a fine-line output of a leader block notch on the magnetic tape to be determined at the appropriate tape threading position.
Rehklau et al. U.S. Pat. No. 4,589,608 discloses a cassette loading apparatus wherein various mechanical devices are adapted to provide for appropriate tape positioning in the loading of a magnetic tape cassette. There is no disclosure of an electromagnetic or electrostatic detection arrangement or sensors for determining the placement of the pins on magnetic tapes within media cassettes.
Similarly, Baur U.S. Pat. No. 5,454,681 discloses an automatic archiving and retrieval system for computer data storage cassettes. Again, as in the previously referenced publications, there is no disclosure of any electrostatic detection or electromagnetic sensor means for determining the proper placement of a pin on a magnetic media tape within a cartridge shell.
Japanese Patent Publications JP 1222888A and JP 63053771A each disclose cartridge magazines and methods for detecting pin positioning by means of a robot. However, this type of structure does not concern itself with the positioning of a pin on a tape within a cartridge shell adapted to provide for the feed of a magnetic tape.
The foregoing is also set forth in Japanese Patent Publication JP62062252A, wherein a pin position detector is provided for primarily detecting pins on an integrated circuit package, and is not designed for the pin picking or placement in a magnetic tape cartridge through the intermediary of either electromagnetic or electrostatic detection means or sensors.
Moreover, IBM Technical Disclosure Bulletin, Volume 23, No. 4 of September 1980, pages 1657 and 1658 relates to an arrangement for detecting a web or tape wrapped on a hub. In that instance, the detection arrangement senses as to when more than one turn of a magnetic tape is wrapped around the hub of a take-up reel. There is no consideration given to the placement or correct positioning of a tape leader pin in a media cartridge analogous to that provided for by the present invention.
Accordingly, in order to improve upon the present state-of-the technology in the determination or sensing of a position of a pin on a tape within a cartridge shell, particularly for but not limited to media cartridges such as LTO cartridges, in order to attain tape drive reliability, the invention provides for the detection of pin location from the exterior of the cartridge in either electromagnetic or electrostatic modes without having to physically enter the interior of the cartridge shell. This sensing or detection of the pin can be readily achieved by monitoring the changes in the electrical properties of an electromagnetic circuit, or through the intermediary of electrostatic detection means.
In particular, the correct position of the pin on the tape leader within the cartridge shell can be readily determined, pursuant to a first embodiment, by positioning an electromagnetic circuit in the drive at such a position whereby the pin alters the inductance of the electromagnetic circuit when it is located in the correct position in the cartridge upon the cartridge being properly located within the drive. Basically, the inductance will be reduced for pins which are made of a conductive ferrous material; for instance, iron/steel. Non-ferrous pins; or stainless steel pins do not cause the inductance to be reduced, but modified by the introduction of eddy currents into the pins. In this connection, the sensing of the pin in the cartridge is achieved by locating the electromagnetic circuit at opposite external ends of the pin, and whereby alternative electromagnetic circuits can be employed depending upon the sensitivity and electromagnetic and conductive properties of the pin, in this instance, being possibly constituted of a stainless steel material as commonly employed in LTO cartridges.
Alternatively, in particular instances when it is not desired to provide for a pin on the tape which is constituted of such a metallic, electromagnetically-sensed material, rather than the foregoing, sensing is effected through electrostatic detection means.
Pursuant to specific embodiments of the invention, electromagnetic circuitry can be employed in order to detect both the top and bottom of the tape leader pin independently if each other, and which renders it able to derive the positioning or possible misalignment of the pin on the tape at opposite sides of the cartridge shell.
Pursuant to a further arrangement of the invention, multiple sensors can be arranged on each side of the cartridge, so as to facilitate monitoring the pin position during picking and placement of the pin in the cartridge. In that type of arrangement utilizing multiple pin sensing structure, it is possible to detect the situation in which the pin has proper placement and is being extracted from the media cartridge in the proper orientation thereof. However, upon detection of the pin as not being picked properly, error recovery procedures can be implemented in an attempt to appropriately align the pin in the media cartridge, or to abort the loading thereof prior to removing the pin from the cartridge, subsequent to which it would be impossible to replace the pin if improperly oriented.
Accordingly, it is an object of the present invention to provide for a novel arrangement for sensing the position of a pin on a tape within the cartridge shell of a media cartridge.
Another object of the invention is to provide for an arrangement for sensing the position of a pin on a tape within a cartridge shell, which the opposite ends of the pin are electromagnetically sensed or electrostatically detected independently of each other from the exterior of the cartridge shell.
Yet another object of the present invention is to provide an arrangement for sensing the pin in a cartridge, such as a media cartridge in an electromagnetic mode, or electrostatically, whereby multiple sensors may be provided on opposite sides of the cartridge to enable monitoring the pin position within the media cartridge.
Still another object of the present invention is to provide an arrangement for sensing the pin in a magnetic tape cartridge through the utilization of an electrostatic detection mode.
A still further object resides in a provision of a method for electromagnetically sensing the position of the pin on a tape within a cartridge shell of a media cartridge.
A yet further object of the invention resides in the provision of a method for sensing the position of a pin on a tape within a cartridge shell through the application of an electrostatic detection mode.
Yet another object of the present invention is to provide a method for the detection of pins within an media cartridge the type described wherein a plurality of pin sensing arrangements are provided to enable detection as to the proper positioning of the pin upon being picked and being extracted from the cartridge in a proper orientation.